Recent advances in semiconductor fabrication and processing have led to the increased use of electroplated tin-silver alloys. Some exemplary applications of tin-silver alloys are disclosed in U.S. Pat. Pub. No. 2012/0138471 (of U.S. patent application Ser. No. 13/305,384), entitled “ELECTROPLATING APPARATUS AND PROCESS FOR WAFER LEVEL PACKAGING,” hereby incorporated by reference in its entirety and for all purposes. In many of these applications, tin-silver alloys derive their utility, at least in part, from a superior resistance to tin whisker formation, available reasonably stable plating baths and processes, a lower solder melting point, and improved resistance to solder ball connection breaking under shock forces. However, the electroplating of tin-silver alloys onto semiconductor substrates has oftentimes found to be problematic due to the buildup of spurious tin-silver deposits on the electroplating apparatus itself. In particular, it has been found that tin-silver buildup on and around the lipseal and/or cup bottom regions of an electroplating device's substrate holder—or clamshell assembly—may lead to significant processing difficulties. Such spurious metal accumulation, generally referred to herein as “lipseal plating” may even, in some circumstances, cause the seal formed between the substrate and lipseal to fail. The result is that the inner portions of the clamshell assembly become contaminated with potentially harmful and corrosive electroplating solution.
Because “lipseal plating” can lead to lipseal failure, it is typically necessary to remove or clean away spurious tin/silver deposits from the lipseal and/or cup bottom regions, periodically, over the course of a sequence of electroplating operations. Current cleaning techniques involve regular periodic cleaning with a nitric acid solution by manually wiping the lipseal region with a hand-held swab which has been dipped in the nitric acid solution. Once swabbed with nitric acid, deposits on the lipseal and/or cup bottom dissolve, and these regions are subsequently rinsed to remove the acid solution and dissolved deposits. However, these procedures are error prone, either because not all deposits are removed, or because too much force is applied causing the swab to damage the relatively fragile lipseal contact region. Furthermore, when the spurious depositions are substantial, manual wipe down techniques may simply be insufficient, and some components of an electroplating apparatus may need to be removed and replaced. Often, these preventive operations need to be performed on a daily basis—a significant challenge in production environments utilizing multiple tools and where high production volumes are required. Thus, the current techniques for removing spurious metal deposits from the lipseal and/or cup bottom regions of electroplating devices are inefficient and inadequate at best.